PROJECT SUMMARY Alcohol use disorders (AUDs) are common, enduring, frequently recurring, and often involve comorbid substance use disorders (SUDs) or other psychiatric disorders. Despite the importance of AUDs as a public health concern, important gaps in knowledge remain concerning events or processes that culminate in the comorbidity of AUD with SUDs and other psychiatric conditions, and the impacts that such forms of comorbidity have on the course and outcomes of AUD. To address these gaps, the proposed secondary analysis research will utilize an existing prospective and multigenerational data set from the Oregon Adolescent Depression Project (OADP), a community- based study with a regionally representative cohort sample followed throughout the high-risk periods of adolescence, emerging adulthood, and young adulthood. In this proposal we describe a plan for investigating (1) the diversity of risk-related developmental pathways that predict AUD alone versus comorbid AUD with a non-alcohol SUD; and, (2) whether AUD remission or recovery is associated with a heighted risk for the emergence of a different SUD as suggested by the drug substitution hypothesis. In conjunction with our investigation of these topics, we will also conduct exploratory analyses that evaluate sex differences, sex moderation, and sex invariance. Findings from these projects are expected to make significant and important contributions to current understandings of factors related to the course of AUDs and, consequently, future refinements in etiologic theories of alcoholism and the design of tailored prevention and treatment interventions.